Defensive end Anthony Spencer will undergo surgery on his left knee later this week and is expected to miss two to four weeks, NFL.com reported Tuesday afternoon. Coach Jason Garrett confirmed Spencer’s surgery to the website.

Anthony Spencer will undergo knee surgery. (AP Photo)

Spencer, who is making the transition to 4-3 defensive end after playing outside linebacker in the team's former 3-4 scheme the past four seasons, is expected to be ready for the regular season.

He suffered his current injury during conditioning tests when the team first reported to training camp last weekend. He also had bruised the knee during offseason workouts.

Spencer is the Cowboys' third defensive lineman to get injured already. End Tyrone Crawford is out for the season after tearing his Achilles’ tendon on Sunday. Tackle Jay Ratliff is on the physically unable to perform list after suffering a hamstring injury on Saturday.